This present disclosure relates generally to a broach tool and methodology for designing broach tool rake surfaces.
Gas turbine engines, such as those that power modern commercial and military aircraft, generally include a compressor section to pressurize an airflow, a combustor section to burn a hydrocarbon fuel in the presence of the pressurized air, and a turbine section to extract energy from the resultant combustion gases.
The compressor and turbine sections include components that rotate at high speeds, which subject the components to significant centrifugal loads. One component that rotates at high speeds is a disk that carries multiple circumferentially arranged rotor blades. The blades are typically attached at an outer circumference of the disk through respective blade attachment slots. Each of the slots has a profile that corresponds with the root of the blade, and has a configuration designed to retain the blade in the slot. The blade attachment slots are generally of a “fir-tree” configuration to increase the load bearing surface area. Broaching is a process often utilized to machine the fir-tree slots.
Limitations of known broach processes associated with aerospace materials may include excessive material strain hardening, surface microstructure alteration (such as white etched layer and bend microstructures), slot deformation due to high friction forces affecting dimension accuracy of the slot, and ripple formation on the slot surfaces.